14 awg is never big enough for an amp. I have seen 10 awg power cords make huge difference in 5 wpc amps.
The logic of @johnnycamp5 above is exactly why so many people have undersized power cords for their amps. But I'm ok with that. I've bought 2 excellent amps used and cheap that I concluded were sold because the owners had undersized power cords on them.
Jerry